linux-kernel - Re: [PATCH 2/2] Revert "f2fs: add ovp valid_blocks check for bg gc victim to fg

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Date:   Sat, 5 May 2018 13:37:05 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     <jaegeuk@...nel.org>
CC:     <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, <chao@...nel.org>
Subject: Re: [PATCH 2/2] Revert "f2fs: add ovp valid_blocks check for bg gc
 victim to fg_gc"

Ping,

On 2018/4/27 10:55, Chao Yu wrote:
> Hi Jaegeuk,
> 
> Missed this patch, or any problem in it?
> 
> Thanks,
> 
> On 2018/4/26 17:05, Chao Yu wrote:
>> For extreme case:
>> 10 section, op = 10%, no_fggc_threshold = 90%
>> All section usage: 85% 85% 85% 85% 90% 90% 95% 95% 95% 95%
>>
>> During foreground GC, if we skip select dirty section whose usage
>> is larger than no_fggc_threshold, we can only recycle 80% invalid
>> space from four 85% usage sections and two 90% usage sections,
>> result in encountering out-of-space issue.
>>
>> This reverts commit e93b9865251a0503d83fd570e7d5a7c8bc351715 to
>> fix this issue, besides, we keep the logic that we scan all dirty
>> section when searching a victim, so that GC can select victim with
>> least valid blocks.
>>
>> Signed-off-by: Chao Yu <yuchao0@...wei.com>
>> ---
>>  fs/f2fs/f2fs.h    |  3 ---
>>  fs/f2fs/gc.c      | 16 ----------------
>>  fs/f2fs/segment.h |  9 ---------
>>  3 files changed, 28 deletions(-)
>>
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 64e3677998d8..9f8b327272df 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -1192,9 +1192,6 @@ struct f2fs_sb_info {
>>  	struct f2fs_gc_kthread	*gc_thread;	/* GC thread */
>>  	unsigned int cur_victim_sec;		/* current victim section num */
>>  
>> -	/* threshold for converting bg victims for fg */
>> -	u64 fggc_threshold;
>> -
>>  	/* threshold for gc trials on pinned files */
>>  	u64 gc_pin_file_threshold;
>>  
>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>> index 3134dd781252..62eba4a71123 100644
>> --- a/fs/f2fs/gc.c
>> +++ b/fs/f2fs/gc.c
>> @@ -263,10 +263,6 @@ static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
>>  	for_each_set_bit(secno, dirty_i->victim_secmap, MAIN_SECS(sbi)) {
>>  		if (sec_usage_check(sbi, secno))
>>  			continue;
>> -
>> -		if (no_fggc_candidate(sbi, secno))
>> -			continue;
>> -
>>  		clear_bit(secno, dirty_i->victim_secmap);
>>  		return GET_SEG_FROM_SEC(sbi, secno);
>>  	}
>> @@ -406,9 +402,6 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>>  			goto next;
>>  		if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
>>  			goto next;
>> -		if (gc_type == FG_GC && p.alloc_mode == LFS &&
>> -					no_fggc_candidate(sbi, secno))
>> -			goto next;
>>  
>>  		cost = get_gc_cost(sbi, segno, &p);
>>  
>> @@ -1152,17 +1145,8 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
>>  
>>  void build_gc_manager(struct f2fs_sb_info *sbi)
>>  {
>> -	u64 main_count, resv_count, ovp_count;
>> -
>>  	DIRTY_I(sbi)->v_ops = &default_v_ops;
>>  
>> -	/* threshold of # of valid blocks in a section for victims of FG_GC */
>> -	main_count = SM_I(sbi)->main_segments << sbi->log_blocks_per_seg;
>> -	resv_count = SM_I(sbi)->reserved_segments << sbi->log_blocks_per_seg;
>> -	ovp_count = SM_I(sbi)->ovp_segments << sbi->log_blocks_per_seg;
>> -
>> -	sbi->fggc_threshold = div64_u64((main_count - ovp_count) *
>> -				BLKS_PER_SEC(sbi), (main_count - resv_count));
>>  	sbi->gc_pin_file_threshold = DEF_GC_FAILED_PINNED_FILES;
>>  
>>  	/* give warm/cold data area from slower device */
>> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
>> index 7702b054689c..c385daabcb67 100644
>> --- a/fs/f2fs/segment.h
>> +++ b/fs/f2fs/segment.h
>> @@ -774,15 +774,6 @@ static inline block_t sum_blk_addr(struct f2fs_sb_info *sbi, int base, int type)
>>  				- (base + 1) + type;
>>  }
>>  
>> -static inline bool no_fggc_candidate(struct f2fs_sb_info *sbi,
>> -						unsigned int secno)
>> -{
>> -	if (get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true) >
>> -						sbi->fggc_threshold)
>> -		return true;
>> -	return false;
>> -}
>> -
>>  static inline bool sec_usage_check(struct f2fs_sb_info *sbi, unsigned int secno)
>>  {
>>  	if (IS_CURSEC(sbi, secno) || (sbi->cur_victim_sec == secno))
>>
> 
> 
> .
>